1. Field of the Invention
This invention relates generally to livestock watering tanks and more specifically to insulated livestock watering tanks for use in particularly cold or particularly hot environments.
During winter, in cold regions such as Canada and the northern United States, it is common for the water in livestock watering tanks to freeze over. As livestock are in constant need of water, the farmer must spend a considerable amount of time ensuring that the water in the livestock watering tanks is not frozen. An insulated watering tank prevents freezing. Similarly, in hot environments, the insulated tank keeps the water relatively cool.
2. Description of the Prior Art
A number of livestock watering tanks have been proposed to overcome this problem. Examples of such tanks can be found in U.S.Pat No. 4,559,905 granted to Ahrens on Dec. 24, 1985; and U.S. Pat. No. 3,745,977 granted to Martin on Jul. 17, 1973. Both of these patents disclose insulated tanks having buoyant floats which close off the opening. The float is pushed out of the way by the animal as it drinks from the tank. The float returns to its resting position when the animal is finished drinking, thereby closing the opening. Conventional ball-cock float valves are provided in the tank to replenish the water in the tank, the valve being connected to a water supply line.
As pointed out in the introductory paragraphs of the above-mentioned Ahrens U.S. patent, conventional tanks of such a type are subject to certain problems. For example, as recited in that patent,
". . . spring-loaded doors have a tendency to close upon the head of the animal or otherwise punch the animal during drinking. Also, the buoyant floats are generally flat and can become misaligned such that the opening is not completely sealed. Also, the flat float requires the animal to exert and maintain considerable force on the float with its nose or muzzle to submerge the float to provide access to the water."
The Ahrens apparatus purports to overcome these problems, and to some extent may do so, but the Ahrens apparatus has certain problems of its own, including relative complexity of the structure.
It is also known in the prior art to have spring-loaded doors instead of buoyant floats.
Generally, the prior art devices require significant force exertion by the animal to gain access to the water, which means that smaller animals such as hogs less than 100 pounds or sheep may have difficulty in gaining access, or indeed it may be impossible for them to gain access.
In addition to the above problems, the prior art devices tend to encounter problems with the doors freezing to the tanks.
In summary, the main problems in the prior art include some or all of the following: (1) excessive force being required to gain and maintain access to the water; (2) inadequate sealing for one reason or another; and (3) freezing of the door to the surrounding tank structure.